Torpedo exploder mechanism



Oct.v 4, 1960 J. KENDALL El-AL 2,954,734

TQRPEDO EXPLODER MECHANISM Filed Oct. 1?. 1947 5 Sheets-Sheet 1 (K)- OOEFFICIENT 0F PRESSURE (X)'DISTANCE FROM NOSE 3mm Jmndall fi mnderson (L) LENGTH OF TORPEDO PERGENT OF LENGTH Oct. 4, 1960 J. M. KENDALL ETAL 2,954,734

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United States Patent 2,954,734 TORPEDO IEXPLODER MECHANISM James M. Kendall, Coral Hills, Md., and George A. Henderson, Syracuse, N-Y.

Filed Oct. '17, 1947, Ser. No. 780,562 '26 Claims. (Cl. 102-70.2)

(Granted under Title 35, US. Code (1952), sec. 266) This invention relates generally to a torpedo exploder and more particularly to an exploder mechanism for an electrically propelled homing type torpedo which is adapted to be launched from a submarine below the surface of the water and to attack a surface target vessel in an upward sweep toward the keel thereof.

A homing'torpedo is known in the art of marine warfare as one which is provided with a steering device responsive to some characteristic of the target vessel such, for example, as microphones responsive to the'acoustic signals transmitted through the surrounding water by the propeller of the target vessel and which employs means controlled by the microphones for steering the torpedo to the target vessel.

A device adapted to accomplish the foregoing steering operations is described and illustrated in US. Patent 1,121,563 issued to Karl 0. Leon for Automatic Steering Apparatus.

In certain of the exploder mechanisms heretofore devised for use in torpedoes adapted to be launched under water from submarines, an impeller wheel and an associated gear reduction is employed as the motive means for driving the arming device of the exploder mechanism whereby the firing circuit of the mechanism is not rendered effective until the torpedo has moved a safe distance away from the launching craft. Such an arrangement, for example, is disclosed in the copending application of James M. Kendall et al., Serial No. 750,615, filed May 16, 1847, for Torpedo Exploder Mechanism. This arrangement has not been found to be entirely satisfactory for use with homing type torpedoes for the reason that the impeller drive mechanism is noisy in operation and produces acoustical disturbances in the surrounding water which interfere with the intended operation of the steering apparatus in response to the sound signals received from the propeller of the target vessel. 7

Torpedoes are known to broach during their runs, a

broach being defined as any phase of travel of the torpedo during its run in which the warhead or any part thereof moves out of the water. A-homing torpedo which is fired from an underwater position and adapted to make an upsweep approach to the target vessel so as to strike the bottom thereof, is very likely to broach in the event that the torpedo should miss the target vessel. In such case, upon reentering the water, the inertia switch may be actuated due to the impact of the torpedo with the surface of the water, the firing circuit closed, and the torpedo exploded. This not only would apprise thetarget vessel that it is under attack but the explosion destroys the torpedo itself, rendering it impotent for making a return run and a second strike at the target vessel.

Moreover, in other devices of the prior art wherein the impeller wheel is located in the nose of the torpedo, the impact of the torpedo with the target vessel causes coillapse of the impeller mechanism and cushioning of the impact blow with the result that the inertia responsive switch in the firing circuit frequently fails to respond to 2,954,734 Patented Oct. 4, 1960 ice the cushioned blow, particularly when the torpedo is moving at slow speeds.

An object of the present invention is to provide a new and improved torpedo exploder mechanism for a homing type torpedo.

Another object is to provide a new and improved exploder mechanism for an acoustically responsive homing type torpedo in which the mechanism is adapted to be armed without producing acoustical disturbances within the surrounding water.

Another object is to provide electroresponsive means for arming the firing circuit of an electrically driven torpedo and to adapt the arming means and the firing circuit for operation from the electrical power source of the torpedo.

A further object is to provide a torpedo exploder mechanism which is adapted to be armed a predetermined interval of time after the difference in the dynamic pressure between the nose and side wall of the torpedo reaches a predetermined value whereby the torpedo invariably moves a safe distance away from the launching craft before the exploder mechanism becomes armed.

A still further object is to provide a new and improved torpedo exploder mechanism having means for indicating that the torpedo exploder has been moved into the armed condition thereof prior to launching of the torpedo into the water.

Still another object is to provide an exploder mechanism which is ineffective to fire the torpedo when the torpedo is below a predetermined depth of submergence.

An additional object of the present invention resides in the provision of an inertia responsive torpedo exploder mechanism which is adapted to be mounted within a handhole in the nose of a torpedo.

Still an additional object of the present invention resides in a torpedo exploder mechanism which has no external operating part-s susceptible of damage during handling.

Still another object of the invention is to provide a new and improved firing circuit for a homing type torpedo in which the firing circuit is rendered ineffective to fire the torpedo in response to the impact thereof with the surface of the water following a breach.

Still other objects, advantages and improvements will be apparent from the following description taken in connection with the accompanying drawings, in which:

Fig. 1 is a diagrammatic view of a torpedo employing the exploder mechanism of the present invention according to the preferred embodiment thereof and illustrating the variation in the dynamic pressure of the surrounding water from the nose of the torpedo backward along the side wall thereof;

Fig. 2 is a view in elevation of the exploder mechanism mounted in the nose of the torpedo;

Fig. 3 is a view partly in elevation and partly in section of the exploder mechanism rotated'l80 degrees from the view shown in Fig. 2;

Fig. 4 is a schematic perspective view of the arming indicator mechanism;

Fig. 5 is a sectional view taken along line 5--5 of Fig. 3;

Fig. 6 is an end view of the exploder mechanism as seen substantially along the line 66 of Fig. 3 with the top plate removed;

Fig. 7 is a diagrammatic view of the warhead of the torpedo illustrating the complete electrical system of the torpedo exploder mechanism of the present invention;

Fig. 8 is a sectional view of the motor cut-off switch in the cut-off position thereof;

Fig. 9 is a sectional view of the rearward end portion of the exploder mechanism illustrating the position of various parts thereof when the exploder mechanism is in the armed condition;

Fig. is a view partly in elevation and partly in section of the fluid pressure differential responsive switch illustrating the manner of mounting thereof;

Fig. 11 is a sectional view of the depth responsive switch illustrating the manner of mounting thereof;

Fig. 12 is a view in elevation of the inertia responsive switch mounted in position on the supporting plate therefor; and

Fig. 13 is a sectional view taken substantially along the line 13-43 of Fig. 12.

Referring now to the drawings and more particularly to Figs. 1 and 2 thereof, there is shown thereon a torpedo generally designated 10 and having an exploder mechanism 11 mounted in a handhole 12 provided in the nose of the torpedo. A bulkhead located at 13 separates the warhead 14, which contains the main explosive charge, from the rear compartments of the torpedo. The rear compartments contain the propulsion and steering mech anisms (not illustrated) for operating the torpedo electrically from the source of power comprising storage batteries BA, Fig. 7. Exploder mechanism 11 is secured within handhole 12 in watertight relation therewithin by means of a threaded locking ring 50 which forces base 24 against flange 16 of the handhole structure as the ring is tightened, a ring gasket 81 being interposed between the ring and base 24 and a pair of ring gaskets 30 being inserted in annular grooves 20 provided therefor in the base to form a watertight seal between the base and the wall of the handhole as the gaskets are forced thereagainst upon tightening the locking ring.

The exploder mechanism 11 employs a fluid pressure differential responsive switch for initiating operation of the delayed arming device of the mechanism, hereinafter to be described, as the switch closes in response to a predetermined difference in the dynamic pressure developed between the nose and side wall of the torpedo as the torpedo moves away from the launching craft.

Switch 15 is provided with a pair of high pressure ports or conduits 17, Fig. 10, in communication with the surrounding water at the nose of the torpedo and a low pressure port 18 which is in communication with the surrounding water at port 19 in the side wall of the torpedo by way of conduit 21, annular groove 22 and bore 23 in the supporting base 24 of the exploder mechanism, and thence by way of conduit 25 to the low pressure port 18.

Switch 15 preferably is similar to the difierential pressure switch disclosed and claimed in the copending application of James M. Kendall for Fluid Pressure Differential Switch, Serial No. 758,969, filed July 3, 1947.

Referring now more particularly to Fig. 10, it will be seen that switch 15 is secured to supporting base 24 preferably by means of a locking ring 26 in threaded engagement with shank 27 of the switch through which high pressure ports 17 extend, the shank projecting through a flanged opening in the base and a ring gasket 28 being interposed between the switch and flange 16 in the supporting base to form a watertight seal therebetween.

Referring now to the graphical portion of Fig. l wherein the zero dynamic pressure value corresponds to the static pressure of the surrounding water at the depth of submergence of the torpedo therein, it will be seen that the dynamic pressure on the outer surface of the torpedo, as it moves through the water, is a maximum at the nose of the torpedo and decreases rearwardly thereof to zero value at a point on the side wall of the torpedo at which port 19 is located and at which the dynamic pressure is Zero regardless of the speed of the torpedo. For different speeds of the torpedo, the dynamic pressure, as a function of the position along the torpedo side wall, has different values.

Beyond port 19 the dynamic pressure decreases to a maximum negative value at point 29 on the surface of the torpedo and thereafter increases approximately to zero value at the point where the hemispherical nose merges with the cylindrical side wall, the pressure thereafter along the cylindrical side wall remaining substantially constant at a small negative value.

The pressure at any point along the side wall of the torpedo starting from the nose in an aft direction may be determined from the equation P=pd+K( /2pv The position along the side wall is conveniently measured in units of X/L where X/ L is the percent of length of the torpedo; L is the length; and X is the distance back from the nose of the torpedo.

Referring now to Fig. 11, it will be seen that the exploder mechanism 11 also includes a hydrostatic depth responsive switch 31 disclosed and claimed in divisional application of James M. Kendall et al., Serial No. 456,890, filed September 17, 1954, now US. Patent No. 2,777,028, for Hydrostatic Pressure Switch. Switch 31 has a water inlet port 32 in communication with the surrounding water by way of conduit 21 and annular groove 22 in the supporting base 24 and radial bores 39 and 38 in the supporting base and switch respectively.

Switch 31 is secured'to supporting base 24, preferably by means of a locking ring 33 in threaded engagement with a shank 34 in which shank water inlet port 32 and radial bore 38 are formed, the shank projecting through an opening with a flange 3 7 in the base and a ring gasket 35 being interposed between the switch and flange 37 to form a watertight seal therebetween.

Shank 34 is integrally formed with an enlarged tubular casing 45 within which is arranged a diaphragm assembly comprising a pair of flexible diaphragrns 62 and 65 and a tubular spacing member 69 therefor having a dividing wall 71. The diaphragm assembly is urged against a cushioning gasket 43 by an insert 46, formed of any suitable phenolic material, and secured within casing 45 by crimping the ends thereof, substantially as shown. Bore 49 in the insert forms a chamber into which extend a pair of spaced J-shaped terminals 48 which preferably are molded in the insert. Bore 49 is closed by an adjustable cupshaped screw 52 which forms a seat for a coil spring 54.

The other end of spring 54 is seated on a flanged tubular bushing 55 formed of electrical insulating material. The bushing forms an abutting surface between spring 54 and electroconducting disk 57 which is yieldably urged into contact with terminals 48 by the spring. Disk 57 is axially offset as at 58 to provide a seat for the pointed end 59 of piston rod 61, the projection resulting from. the offset forming a means for centering bushing 55 on the disk. Piston rod 61 is slidably supported within a reduced bore '63 in insert 46, and has a head 64 secured thereto at the opposite end thereof, head 64 being arranged in abutting relation with diaphragm 62 whereby the pressure of the surrounding water applied to the diaphragm assembly is imparted to disk 57. The insert is provided with an enlarged bore 70 to permit axial movement of head 64 therein.

Spacing member 69 of the diaphragm assembly is formed with an annular groove 68 whereby diaphragms 62 and 65, which are formed substantially C-shaped in cross section, may be mounted on the spacing member in interfitting and fluid tight relation therewith and form with dividing wall 71 a pair of chambers 72.

Dividing wall 71 in member 69 is provided with orifices 73 therethrough whereby the flow of fluid between the pair of chambers 72 is restricted as the diaphragms are flexed. This provides a dash pot arrangement which suppresses such movement of parts as would cause opening of the switch in response to suddent shocks resulting, for example, from impact of the torpedo with a target vessel. A suitable fluid having a flat viscosity characteristic with temperature such, for example, as 35 centistoke silicone oil may be employed and may be filled in any suitable manner which renders the fluid free of air bubbles and air pockets. The pressure of the surrounding water applied externally to diaphragm 65 is applied to diaphragm 62 by way of the fluid in chambers 72 and thence to piston head 64. Thus, when a predetermined fluid pressure corresponding to a predetermined depth of submergence and determined by the initial spring rate of spring 54 and adjustment of screw 52 is applied to diaphragm 65, piston rod 61 is moved against the opposing force of spring 54 to move contact disk 57 out of engagement with terminals 48 thereby to interrupt the circuit including switch 31.

The exploder mechanism also includes an inertia actuated switch 74 which is adapted to close the firing circuit of the exploder in response to the impact of the torpedo with its target vessel and which is adapted to prevent closing of the circuit in response to the impact of the torpedo with the surface of the water following a broach, or in response to counter mine shocks in the surrounding water.

Referring now more particularly to Figs. 12 and 13, it will be seen that the inertia switch comprises a flanged cylindrical base 75 formed of any suitable electrical insulating material. Base 75 have a portion 77 fitted within a circular recess 78 formed in supporting base 24 and the flange thereof is recessed to receive a pair of clamping members 79 also formed of electrical insulating material. The clamping members and base member 75 are secured to base 25 by screws 83 received in suitable apertures formed therefor in these members. Toes 84 radially extending from an electroconducting housing 89 are secured between clamping members 79 and base 75, thereby to secure housing 89 to base 75 and to position electroconducting cup member 85 of substantially hemispherical shape Within a recess 86 formed therefor within base 75. Member 85 is fitted in matching engagement with housing 89 and preferably the two are soldered together to insure a positive electrical connection therebetween.

The opposite end of housing 89 is formed with a rounded wall portion having a central opening therethrough and is strengthened by a washer 87 secured thereto in alignment with the central opening. A flexible lead wire terminal 94 having a soft metal sheath 92 extends through the central opening and is insulated and supported therewithin as by a Kovar seal generally designated 91 and including an insulator 95.

Seat member 96, made of suitable electrical insulating material and formed to interfit the rounded end portion of housing 89, is secured therewithin by the cylindrical portion 97 of a spring seat 98 which is generally of tubular configuration and is also formed of electrical insulating material. Spring seat 98 has a projection 101 of electrical insulating material and is fitted within housing 89 and cup member 85 with the projection 101 disposed along the bottom of the cup member. An olfset 102 in housing 89 extends into an opening 105 therefor in spring seat 98 whereby the spring seat is fixed in the proper position within the housing.

A support member generally designated 103 is provided with an annular flange 104 which is yieldably urged into abutting engagement with seat member 96 by a coil spring 106 interposed between support member 103 and seat 98 therefor.

Stem 108 of the inertia member generally designated 107 is slideably mounted within a tubular portion 112 forming part of support 103, said stem 108 having a head 109 normally urged into abutting relation with a shoulder 111 formed in support member 103 at the inner end of tubular portion 112 by a coil spring 117 sleeved about the tubular portion and seated on the opposite end thereof in an opening 116 therefor formed in an inertia ball 113 carried on stem 108.

Flexible terminal 94 is secured to head 109 with sufficient slack to allow support member 103 to freely move away from seat member 96 which serves as a seat therefor. Flange 104 of member 103 is formed with a knife edge as at to permit tilting movement thereof in response to lateral movement of ball 113.

Inertia ball or member 113 is provided with a pair of diametrical intersecting bores 114 and 115 therethrough. Stem 108 is fitted within bore 115 and secured therewithin by inserting suitable tools within bore 114 to upset the portion of the stem 108 within bore 114.

Spring 106 normally tends to yieldably position ball 113 substantially centrally of cup member 85, and spring 117, in normally maintaining head 109 in abutment with shoulder 111, normally positions ball 113 out of engagement with a seat therefor formed in spring seat 98.

Switch 74 is mounted with the axis of the stem 108 perpendicular to base 24 substantially axially of the torpedo, with projection 101 disposed beneath ball 113.

When the torpedo strikes a target vessel with a resulting set forward force which exceeds a predetermined force determined by the initial compression and spring rate of spring 106, ball 113 is moved axially of stem 108 against the opposing force of spring 106 into engagement with cup member 85 to complete an electrical circuit between lead 94 and terminal 99 secured to the metallic housing of seal 91, in turn secured to housing 89.

When the switch is subjected to an impact blow from the bottom of the torpedo such, for example, as when the torpedo falls back on the surface of the water following a broach, ball 113 moves into engagement with insulating projection 101 which thus prevents contacting of the ball with member 85 and completion of an electrical circuit therebetween.

When the inertia member 113 is subjected to a set back force, for example, as when the torpedo is subjected to countermine shocks rearwardly thereof, ball 113 overcomes the force of spring 117 and moves rearwardly into engagement with seat 120 in which position of the ball lateral movement thereof is prevented.

Referring now more particularly to Fig. 3, it will be seen that supporting base 24 is provided with a partially threaded bore 119 for receiving a threaded locking ring 122. A transparent member 123, formed of Lucite or the like, is provided with a collar which cooperates with a ring gasket 126 seated against a shoulder 131 in bore 119 to form a watertight seal between member 123 and base 24 when looking ring 122 is sufficiently tightened. The transparent member provides a means for viewing the arming indicator, as will be hereafter more fully described.

'Referring now more particularly to Figs. 2, 3 and 5, there are shown three spacer rods 127 for securing in spaced relation disk shaped intermediate plate 128, gear plate 129 and end plate 130 to supporting base 24.

Intermediate plate 128 is provided with an upstanding portion 132 to which is secured a terminal block 133 for mounting electrical conductors, not shown, for interconnecting various electroresponsive devices of the exploder mechanism disclosed in Fig. 7.

A conventional electrical connector 135 is mounted on plate 128 and serves as a terminal for a cable, not shown, for interconnecting the exploder mechanism with batteries BA located in the torpedo. Plates 129 and 130 are notched as at 82 and 209 respectively to receive the battery cable.

Motor 136 extends through opening 137 in intermediate plate 128 and is urged by strap 138, which is secured to plate 128 by rivets 139, into a registering recess 134 in gear plate 129.

Gear plate 129 forms a support for housing 141 enclosing reduction gears which form a part of the gear train driven by motor 136, Fig. 7, to drive rotor 176. The rotor is mounted in face adjacency with the gear plate, and spur gears 174 and 177 secured respectively to the output shaft of reduction gearing 141 and rotor shaft 201 are arranged in depressions therefor, not shown, in the gear plate.

Referring now more particularly to Fig. 8, it will be seen that gear plate 129 has a threaded opening 143 therethrough for mounting motor cut off switch 142 thereon. Housing 144 of this switch is flanged as at 146 to receive a flanged actuating button 148 of electrical insulating material. The button has a central opening 149 for receiving the reduced end portion of an actuating rod 152 having a coil spring 165 sleeved thereabout and interposed under compression between the button and a contact disk 164 which is loosely carried on the rod. The other reduced end portion of rod 152 is slideably mounted in the central opening 168 of the switch body 156 which is formed of electrical insulating material and secured within housing 144 as by crimping the end of the housing thereagainst as at 158.

Opening 168 is enlarged at 166 to receive a coil spring 175 which is sleeved about the actuating rod and interposed under compression between body 156 and an insulating washer 162 in abutting engagement with the shoulder formed at the enlargement of the actuating rod. This washer also serves as a seat for disk 164 against which it is yieldably urged by spring 165 except when the disk is moved into contact with contact pins 171 which project into a further enlargement 173 of the central opening in body 156. Pins 171 preferably are molded in the body and extend outwardly of the body to form the terminals of the switch.

In the unarmed position of rotor 176, as seen in Fig. 7, the actuating button 148 of switch 142 engages the face of rotor 176 and the button is forced entirely within the switch with the result that disk 164 is yieldably urged into contact with contact pins 171 by spring 165 and spring 175 is compressed. A depression 170 is formed in the face of the rotor to receive button 148 when the rotor has been moved to bring the depression into alignment therewith. When this occurs, the contact disk 164 is moved away from the contact pins under power of spring 175. As the switch opens, the circuit to motor 136 is interrupted to stop the rotor in the armed position thereof, as will appear more fully as the description proceeds.

Referring now more particularly to Figs. 6 and 9, it will be seen that rotor 176 is provided with a recess 179 into which is fitted an insulating member 181 which is secured therewithin by machine screw 182. Electroconducting blade 183, preferably molded within insulating member 181, extends radially from the periphery of rotor 176. Blade 183 is adapted to electrically connect a pair of spaced contacts 184, which together with the blade comprise the arming switch generally designated 185, when the rotor has been moved into the armed position thereof. Each of contacts 184 comprises a pair of spring contact fingers urged together and formed so as to yieldably admit the blade therebetween. Contacts 184 are maintained in spaced and insulated relation as by a block of insulating material 190 secured to gear plate 129 as by a screw 1550.

Referring now more particularly to Figs. 3 to 6 inclusive, wherein is shown the arming indicator generally designated 188 which is provided for visually indicating the armed or unarmed condition, as the case may be, of the exploder mechanism.

Indicator 188 comprises a shaft 192 journallcd in base 24 and plate 130 and having a substantially radially extending arm 178 with a finger 187 which is urged into engagement with cam surface 186 of the rotor 176 by spring 191 which is sleeved about shaft 192 and anchored at the ends thereof to the finger and plate 129 respectively.

Cam surface 186 is provided with recess 193 which is out of registry with the detent portion of finger 187 except when the rotor is in the armed position thereof. Shaft 192 has secured thereto a radially extending shutter 194 which projects adjacent to the inner end of transparent member 123 and is painted with a distinctive color such as red.

Prior to movement of the rotor into its armed position, finger 187 rides on cam surface 186 to position shutter 194 out of registry with transparent member 123, as shown by the solid line portion of Fig. 4. In this case, the red color of the shutter does not appear through the transparent member 123 and indicates that the exploder mechanism is in the unarmed condition.

When the rotor 176 has been rotated into its armed position the detent portion of finger 187 moves into recess 193 whereupon shutter 194 moves into registry with transparent member 123, as indicated by the dotted line portion of Fig. 4. In this case the red color on the shutter appears through the transparent member and indicates that the exploder mechanism is in the armed condition thereof.

Referring now more particularly to Figs. 3 and 6 it will be seen that a pair of keys 196, each secured to gear plate 129 by machine screws 199, extend into a pcripheral groove 198 formed in rotor 176 and serve to maintain the latter in rotatable face adjacency with gear plate 129.

Rotor 176 has a pair of bores (Figs. 6 and 9) therethrough for receiving detonating elements 207 therein such, for example, as tetryl pellets or the like, and an adjacent bore 208 to provide a chamber for expanding gases in the event that one of the detonating elements fires prematurely. When the rotor is in the armed position, elements 207 are in registry with a pair of electroresponsive detonators 206 which are inserted in bores 204 in gear plate 129 and in register with a pair of detonating elements 216 inserted in bores therefore provided in end plate 130.

Detonating elements 216 are disposed in explosive relation to a booster charge 215 carried within a'cup member 214 which is threadedly secured to end plate as at 213. The end plate 130 is provided with a protective skirt 211 which partially encloses rotor 176.

The operation of the exploder mechanism in a homing torpedo will best be understood by reference to Fig. 7 wherein the complete electrical system of the exploder mechanism is diagrammatically disclosed.

When the torpedo has been released from a submerged submarine and attains a predetermined speed through the water such, for example, as 9 knots, the difference in the dynamic pressure of the surrounding water at ports 17 and 19 causes disk 36 of the differential pressure switch 15 to move into engagement with terminals 37 thereof to complete an arming circuit from battery BA for energizing motor 136, this circuit being traced from center tap 217 of battery BA through conductor 218, contacts 37 and disk 36 of the differential pressure switch 15, conductor 219, contact pins 171 and disk 164 of initially closed motor cut oif switch 142, conductor 221, motor 136, conductor 222, and thence to the negative side of battery BA.

The motor operates to drive reduction gearing 141 and spur gears 174 and 177 to cause rotor 176 to rotate slowly in the direction indicated by the arrows. After a predetermined lapse of time, sufficient to permit movement of the torpedo a safe distance away from the launching craft, rotor 176 moves blade 183 into engagement with contacts 184 of arming switch 185, and simultaneously therewith, actuating button 148 of the motor cut off switch 142 drops into depression in rotor 176, thereby to lock the rotor against further rotation and to open cut off switch 142. As switch 142 opens, the aforetraced circuit energizing the motor is interrupted to prevent further operation of the motor 136.

As contacts 184 of the arming switch are bridged by blade 183 thereof, the inertia switch 74 is connected to the electroresponsive detonators 206 which are connected in parallel and only one of which is shown in Fig. 7, thereby to electrically arm the firing circuit of the explorer mechanism. Concurrently with the closing of the arming switch, detonating elements 207 are moved into alignment with detonators 206 and detonating elements 216, thereby to complete an explosive train to the booster charge 215 which is disposed in operative firing relation to the main explosive charge 210 located in the warhead 14, only one of each of detonating elements 207 and 216 being shown in Fig. 7.

When the torpedo strikes a target vessel, the resulting impact causes inertia ball 113 to move into engagement with cup member 85 to complete the firing circuit to the detonators, the firing circuit being traced in Fig. 7 from the positive terminal of battery BA by way of conductor 223, contact terminals 48 and disk 57 of normally closed hydrostatic switch 31, conductor 224, inertia switch 74, conductor 225, arming switch 185, conductor 226, detonator 206, and thence by way of conductor 227 to the negative side of battery BA. As the firing circuit is completed, the detonators are fired and the main charge 210 of the torpedo, in turn, is exploded.

Normally closed hydrostatic switch 31 is adapted to be opened to render the circuit ineffective to fire the detonator in response to operation of inertia switch 74 when the torpedo has submerged beyond a predetermined depth such, for example, as 30 feet, thereby to protect the submarine which launches the torpedo.

In the event that the torpedo misses the target vessel and broaches, or broaches under other conditions, ball 113 of the inertia switch moves into contact with the insulated projection 101 thereof in response to the impact of the torpedo with the surface of the water following the broach. Thus, the inertia switch is rendered inetfective to complete the firing circuit in response to the impact following the broach and thus provides a measure of broach protection which has been found to be entirely satisfactory in use. Moreover, the inertia switch, by reason of the aforedescribed design thereof, provides a measure of protection in preventing closing of the firing circuit in response to countermine shocks, ball 113 in response to shocks received in certain directions to develop sufficient force components moves onto ball seat 120 therefor to prevent lateral movement of the ball and resultant closing of the inertia switch.

From the foregoing, it will now be readily understood that a torpedo exploder has been provided which is well adapted to fulfill the aforestated objects of the invention and whereas but one structural embodiment has been disclosed which gives satisfactory results, it will be apparent to those skilled in the art of marine warfare that additional embodiments and modifications thereof may be made without departing from the spirit and scope of the invention as defined by the appended claims.

The invention herein described and claimed may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. In a torpedo exploder mechanism, the combination of a firing circuit including an electroresponsive detonator, and an inertia actuated switch for rendering said circuit effective to fire the detonator upon impact of the torpedo with a target vessel, said switch comprising a cup shaped contact member and a coacting inertia responsive con-' tacting element therefor, means for yieldably maintaining said element in predetermined spaced relation with respect to the Wall of said cup member, and a strip of insulating material disposed within the cup member beneath the element for preventing contacting between the element and cup member as the element is urged downwardly in response to the impact of the torpedo with the surface of the water following a broach thereof.

2. In an inertia actuated switch of the character disclosed, the combination of enclosing means, an inertia responsive element disposed within said enclosing means and adapted to be urged into a first circuit controlling position therewith in response to set forward and lateral forces applied to the element as a result of shocks received by the switch, means for yieldably urging said element into a second circuit controlling position with respect to said enclosing means, insulating means interposed between the enclosing means and element for preventing the element from moving into said first circuit controlling position when the element is urged in the direction of said insulated means, said element adapted to be moved in response to set back forces applied thereto as a result of shocks received by the switch, and means for preventing movement of the element into the first circuit controlling position in response to lateral force components applied thereto after the element has been moved in response to a set back force.

3. An inertia switch of the character disclosed comprising, in combination, a cup shaped contact member of substantially hemispherical cross section, a ball shaped contact member disposed within the cup member, a stern secured at one end thereof to the ball member, an insulating member for slideably receiving the other end of the stem and having a disk portion terminating in a peripheral knife edge, a hollow insulating member secured to said cup member and having a cylindrical bore therein in registered engagement with said peripheral knife edge and forming a guide for axial movement of said disk portion therewithin and for tilting movement of the first insulating member about the knife edge thereof, a base member, said hollow insulating member having an inwardly extending flange interposed between said ball member and said first named insulating member, a coil spring interposed between said flange and said disk portion for yieldably urging the disk portion against said base member whereby the stem is yieldably maintained in substantial alignment with the axis of the cup member, said flange having a seat formed therein for said ball member, means including a coil spring interposed between the ball member and the first named insulating member for yieldably positioning the ball member away from said seat substantially in concentric alignment with the cup shaped member, and a pair of terminals for the switch including a flexible lead connected to said stem.

4. An inertia switch for use in a torpedo exploder mechanism comprising, in combination, an electroconducting housing, an electroconducting mass within said housing adapted to be moved into engagement therewith in response to the impact of the torpedo with a target vessel, means for yieldably supporting said mass normally in spaced relation with respect to said housing, and electrical insulating means in normally spaced adjacency to said mass interposed between said housing and said mass in a manner to prevent electrical contacting therebetween in response to the impact of the torpedo with the surface of the water following a broach.

5. In a torpedo exploder mechanism, the combination of a firing circuit including an electroresponsive detonator, time delay means for arming the firing circuit in predetermined time delayed relation to the initiation of the operation of the time delay means, pressure differential responsive means, conduit means connecting said last-named means with the water surrounding the nose and side wall of the torpedo, said pressure differential responsive means being adapted to initiate operation of the time delay means when the difference in the dynamic pressure of the surrounding water between the nose and side wall of the torpedo reaches a predetermined value, and inertia means operative when the firing circuit is armed to render the firing circuit eifective to fire the 1 l detonator as the inertia means operates in response to the impact of the torpedo with its target and including means for preventing operation of the inertia means in response to the impact of the torpedo with the surface of the water following a broach.

6. In an exploder mechanism for a torpedo, the combination of a diiferential pressure responsive switch, conduit means connecting said switch with the water surrounding the nose and side wall of the torpedo, said switch being adapted to be closed in response to a predetermined difference in the dynamic pressure between the nose and side wall of the torpedo as the torpedo moves through the water, time measuring means connected to said switch and adapted to be set in operation when the switch is closed, an electroresponsive detonator, an inertia switch adapted to be closed in response to impact of the torpedo with a target vessel, an initially unarmed firing circuit for said detonator including said inertia switch and adapted to be armed by said time measuring means when a predetermined interval of time has been measured thereby whereby the firing circuit is rendered effective to fire the detonator when the inertia switch is closed, and means for visually indicating the armed or unarmed condition of said firing circuit selectively in accordance with the operated or unoperated condition respectively of the time measured means.

7. In an exploder mechanism for a torpedo, in combination, an electroresponsive detonator, a firing circuit for the detonator including an inertia switch and an arming switch, electroresponsive time measuring means adapted when a predetermined interval of time has been measured thereby to close said arming switch thereby to render the firing circuit effective to fire the detonator when the inertia switch is closed in response to the impact of the torpedo with a target vessel, and a differential pressure responsive switch, conduit means connecting said last-named switch with the water surrounding the nose and side wall of the torpedo, said differential pressure responsive switch being adapted to be closed to initiate operation of said time measuring means in response to a predetermined diiference in the dynamic pressure between the nose and side wall of the torpedo as the torpedo moves through the water, and visible means for indicating the armed or unarmed condition of said firing circuit selectively in accordance with the operated or unoperated condition respectively of the time measuring means.

8. In a torpedo exploder mechanism, the combination of a firing circuit including an electroresponsive detonator, time delay switch means for arming the firing circuit in predetermined time delay relation to the initiation of the operation of the time delay means, differential pressure responsive switch means, conduit means connecting said last-named switch means with the water surrounding the nose and side wall of the torpedo for initiating operation of said time delay means when the ditference in the dynamic pressure of the surrounding water between the nose and side wall of the torpedo reaches a predetermined value, and inertia switch means effective to close the armed firing circuit thereby to fire the detonator when the inertia switch means operates in response to the impact of the torpedo with a target vessel and including insulating means for rendering the inertia switch means ineffective to close the firing circuit in response to the impact of the torpedo with the surface of the water following a broach thereof.

9. In an exploder mechanism for a torpedo, the combination of an electroresponsive detonator, a firing circuit for the detonator including an inertia switch, a hydrostatic switch, and an arming switch, electroresponsive time measuring means adapted when a predetermined interval of time has been measured thereby to close said arming switch thereby to render the firing circuit etfective to fire the detonator when the inertia switch is closed in response to the impact of the torpedo with a target vessel, and a differential pressure responsive switch, conduit means connecting said last-named switch with the water surrounding the nose and side wall of the torpedo, said differential pressure responsive switch being adapted to be closed to initiate operation of said timing means in response to a predetermined diiference in the dynamic pressure between the nose and side wall of the torpedo as the torpedo moves through the water, said hydrostatic switch being of a type that is adapted to render said firing circuit ineifective to fire the detonator when the torpedo is below a predetermined depth of submergence.

10. In an exploder mechanism for a torpedo, the combination of an electroresponsive detonator, a source of electrical energy, an initially unarmed firing circuit including an inertia switch for firing said detonator from said electrical source as the inertia switch is actuated in response to the impact of the torpedo with a target vessel, a differential pressure responsive switch, conduit means connecting said last-named switch with the water surrounding the nose and side wall of the torpedo, said differential pressure responsive switch being adapted to be operated in response to a predetermined dilference in the dynamic pressure of the surrounding Water developed between the nose and side wall of the torpedo as the torpedo moves through the water, and means adapted to be set in operation by said pressure responsive switch as the switch is operated and adapted when operation of the means has been continued for a predetermined interval of time to arm said firing circuit.

11. In a torpedo exploder mechanism, the combination of a differential pressure responsive switch, conduit means connecting said switch with the water surrounding the nose and side wall of the torpedo, said switch being adapted to be closed in response to a predetermined difference in the dynamic pressure between the nose and side wall of the torpedo as the torpedo moves through the water, time measuring circuit closing means adapted to be set in operation by said switch when the switch is closed, an electroresponsive detonator, an inertia switch adapted to be closed in response to impact of the torpedo with a target vessel, and an initially unarmed firing circuit for said detonator including said inertia switch and adapted to be armed by said time measuring circuit closing means when a predetermined interval of time has been measured thereby whereby the firing circuit is rendered elfective to fire the detonator when the inertia switch is closed, and indicia means adapted to be actuated by said time measuring circuit closing means for indicating the armed or unarmed condition of said firing circuit selectively in accordance with the operated or unoperated condition respectively of said time measuring circuit closing means.

12. In a torpedo exploder mechanism, the combination of an initially unarmed firing circuit including an electroresponsive detonator, said circuit comprising means including an element responsive to movement of the torpedo through the water for arming said firing circuit in predetermined time delayed relation with respect to the launching of the torpedo into the water, inertia responsive means forming part of said circuit for rendering said armed firing circuit effective to fire the detonator upon impact of the torpedo with a target vessel, and means in said circuit responsive to the pressure of the surrounding water for rendering said circuit ineffective to fire the detonator when the torpedo is below a predetermined depth of submergence.

13. In a torpedo exploder, the combination of an initially unarmed firing circuit including an electroresponsive detonator, time delay means connected to said circuit for arming the circuit in predetermined time delayed relation to the initiation of the operation of the time delay means, pressure differential responsive means, conduit means connecting said last-named means with the water surrounding the nose and side wall of the torpedo, said pressure differential responsive means being adapted to initiate operation of the timing means when the difference in the dynamic pressure of the surrounding water between the nose and side wall of the torpedo reaches a predetermined value, and inertia means in said circuit adapted to render said armed firing circuit eifective to fire the detonator when the inertia means operates in response to the impact of the torpedo with its target, and means responsive to the pressure of the surrounding water for rendering said armed firing circuit inefiective to fire the detonator when the torpedo is below a predetermined depth of submergence.

14. In an exploder mechanism for a torpedo, the combination of an electroresponsive detonator, a source of electrical energy, an inertia switch, means including a differential pressure actuated switch responsive to the difierence in dynamic pressure of the surrounding water between the nose and side wall of the torpedo for connecting said inertia switch to said electrical source in predetermined time delayed relation to the actuation of the differential pressure actuated switch, conduit means connecting said differential pressure actuated switch with the water surrounding the nose and side wall of the torpedo, a firing circuit including said inertia switch for connecting said detonator to said electrical source as the inertia switch is actuated in response to the impact of the torpedo with its target, and means in said circuit responsive to the pressure of the surrounding water for rendering said firing circuit ineifective to fire the detonator when the torpedo is below a predetermined depth of submergence.

15. In an exploder mechanism for a torpedo, the combination of a differential pressure responsive switch, conduit means connecting said switch with the water surrounding the nose and side wall of the torpedo, said switch being adapted to be closed in response to a predetermined difference in the dynamic pressure of the surrounding water between the nose and side wall of the torpedo as the torpedo moves through the water, time measuring circuit closing means adapted to be set in operation by said switch as the switch is closed, an explosive train including an electroresponsive detonator and a movable explosive element initially positioned out of operative firing relation with respect to the detonator and adapted to be moved into operative firing relation therewith by said time measuring circuit closing means in predetermined time delayed relation to the closing of said dilferential pressure responsive switch, an inertia switch adapted to be closed in response to the impact of the torpedo with a target vessel, and a firing circuit including said detonator and said inertia switch and adapted to be armed by said time measuring circuit closing means concurrently with movement of said explosive element into firing relation within said explosive train and adapted to be rendered eifective to fire the detonator when the inertia switch is closed after the firing circuit is armed 16. In a device for exploding a torpedo, the combination of an explosive train including an electroresponsive detonator and a movable explosive element initially out of operative firing relation with said explosive train, a source of electrical energy, means including an electric motor for moving said explosive element into operative firing relation within said explosive train a predetermined interval of time after the motor is connected to said electrical source, an initially open hydrodynamic pressure switch for connecting one side of said electricalsource to one side of said motor when the difference in the dynamic pressure of the surrounding water between the nose and side wall of the torpedo has reached a predetermined value, conduit means connecting said switch to the water surrounding the nose and side wall of the torpedo, an initially closed motor switch interconnecting the other side of said motor and the other side of said electrical source and adapted to be opened by said element moving means to disconnect the motor from the electrical source as the explosive element is moved into operative firing relation within said explosive train, a firing circuit including an initially open arming switch adapted to be closed by said element moving means to partially close said firing circuit concurrently with the opening of said motor switch, a normally open inertia switch in said firing circuit adapted to close said partially closed firing circuit as the inertia switch is closed in response to the impact of the torpedo with a target vessel, and a hydrostatic responsive pressure switch in the firing circuit for rendering the firing circuit inelfective to fire the detonator when the torpedo is below a predetermined depth of submergence.

17. In a torpedo exploder mechanism of the character disclosed, in combination, an electroresponsive detonator, an initially open firing circuit for the detonator including an inertia switch and an initially open arming switch, a diiferential pressure responsive switch, conduit means connecting said last-named switch with the water surrounding the nose and side wall of the torpedo, said differential pressure responsive switch being adapted to be closed in response to a predetermined dilference in the dynamic pressure between the nose and side wall of the torpedo as the torpedo moves through the water, and means controlled by said differential switch for closing said arming switch when the torpedo has traveled a predetermined distance through the water following launching thereof whereby the firing circuit is rendered effective to fire the detonator when the inertia switch is closed in response to the impact of the torpedo with a target vessel.

18. In a mechanism for exploding a torpedo, the combination of a firing circuit including an electroresponsive detonator, time delay switch means for arming said firing circuit in predetermined time delayed relation to the initiation of operation of the time delay means, differential fluid pressure responsive switch means for initiating operation of the time delaymeans when the difference in the dynamic pressure of the surrounding water be tween the nose and side wall of the torpedo reaches a predetermined value, conduit means connecting said differential fluid pressure responsive switch means to the water surrounding the nose and side wall of the torpedo, and inertia responsive switch means in the firing circuit for rendering the armed firing circuit effective to fire said detonator as the inertia responsive switch means operates in response to the impact of the torpedo with a target vessel.

19. In a torpedo exploder mechanism, the combination of a normally open firing circuit including in series a source of electric power, a pressure responsive switch adapted to be closed when the pressure of the surrounding water is less than a predetermined value, an inertia switch adapted to be closed in response to the impact of the torpedo with a target vessel, a normally open arming switch, and an electroresponsive detonator, and means responsive to fluid pressure diiferential between the nose and side wall of the torpedo for closing said arming switch only when the torpedo moves through the water at or in excess of a predetermined speed.

20. In an exploder mechanism adapted to be mounted in a handhole in the nose of a torpedo, the combination of a firing circuit including an electroresponsive detonator, means including a switch for arming the circuit in time delayed relation to launching of the torpedo, means including a differential pressure responsive switch for initiating operation of said arming means when the difference in the dynamic pressure between the nose and a zero dynamic pressure point on the side wall of the torpedo reaches a predetermined value, an inertia switch for rendering the firing circuit efiective to fire said detonator as the inertia switch is actuated in response to the impact of the torpedo with a target vessel, a hydrostatic switch adapted to render the circuit inefiective to fire the detonator when the torpedo moves below a predetermined depth of submergence, means including a plate for supporting said differential and hydrostatic switches and adapted to mount the exploder mechanism in water-tight relation within said handhole, port means in said plate for bringing the surrounding water at the nose of the torpedo into communication with one pressure responsive side of said differential switch, and port means for bringing the surrounding water at said zero dynamic pressure point into communication with the other pressure responsive side of the differential switch and into communication with said hydrostatic switch.

21. In a torpedo exploder mechanism adapted to be mounted in a handhole in the nose of a torpedo, the combination of means including a supporting plate having first and second ports therein and adapted to mount the exploder mechanism in water-tight relation within said handhole, an electroresponsive detonator, an initially unarmed firing circuit, a dynamic pressure differential responsive switch mounted on said supporting plate and having a high pressure responsive surface in communication with the surrounding water at the nose of the torpedo through said first port in the plate and a low pressure responsive surface in communication with the surrounding water at a point on the side wall of the torpedo where the dynamic pressure of the water on said port is zero through said second port in the plate, said dynamic switch being adapted to be operated when the difference in the dynamic pressure between the nose and said point on the side wall of the torpedo has reached a predetermined value, time measuring circuit closing means adapted to be set in operation by said dynamic pressure switch for arming said firing circuit when a predetermined interval of time has been measured by the time measuring means, an inertia switch for rendering the firing circuit effective to fire the detonator when the inertia switch is actuated in response to the impact of the torpedo with a target vessel, and a pressure responsive switch mounted on said supporting plate for rendering the firing circuit ineffective to fire the detonator when the static pressure of the surrounding water exceeds a predetermined value, said last named switch having a pressure responsive surface in communication with the surrounding water through said second port in the plate.

22. A torpedo exploder of the character disclosed comprising, in combination, an electroresponsive detonator adapted when energized to fire the torpedo, a firing circuit for energizing the detonator including a source of electrical energy, an inertia responsive switch initially connected in open circuit relation in said firing circuit and havng an electroconductive housing and an electroconductive mass yieldably supported within said housing and movable into electrical engagement with said housing to complete the firing circuit therethrough responsive to the impact of the torpedo with the target vessel, electrical insulating means interposed between said mass and said housing and constructed and arranged to prevent the completion of said firing circuit in response to a shock applied to said inertia switch from beneath said torpedo, a pressure responsive switch connected in said firing circuit and in series with said inertia responsive switch and comprised of a pair of electrical terminals, yieldable means for electrically connecting said terminals together to complete said firing circuit through said pressure responsive switch to said inertia responsive switch, means including first and second flexible diaphragms arranged to provide a compartment therebetween, a quantity of fluid filling said compartment, duct means for communicating hydrostatic pressure from the surrounding water to the outer surface of the first of said diaphragms to cause deflection of the second of said diaphragms by way of said fluid in the compartment, a plunger operatively connected to said yieldable means and said second diaphragm and movable by deflection of said second diaphragm to direct said yieldable m an from electrical connection between said terminal means to interrupt said firing circuit to said inertia responsive switch when the surrounding water pressure is greater than a predetermined value, time measuring means constructed and arranged to connect said firing circuit to said electrical source in predetermined time delayed relation to the actuation of said time measuring means, and a differential pressure responsive switch means, conduit means connecting said last-named switch means with the water surrounding the nose and side wall of the torpedo for actuating said time measuring means in response to a predetermined dynamic pressure differential in the surrounding water between the nose and side wall of the torpedo as the torpedo moves through the water.

23. A torpedo exploder of the character disclosed including, in combination, a booster charge adapted when ignited to effect the explosion of said torpedo, a firing circuit, an electroresponsive detonator constructed and arranged in said firing circuit to ignite said booster charge when energized, said firing circuit including an inertia responsive switch connected therein and comprised of an electroconductive cup member, an electroconductive mass yieldably supported substantially centrally within and normally in open circuit relation with said cup member and yieldably movable into electrical engagement with said cup member to complete the firing circuit through said detonator in response to an inertia shock when the torpedo strikes a target vessel, insulating means interposed in said cup member between the cup member and said inertia responsive mass and oriented with respect to the underside of the torpedo as it moves through the water to prevent electrical engagement of said mass with said cup member in response to an inertia shock applied to said mass from beneath the torpedo, an initially closed pressure responsive switch arranged in said firing circuit and connected therein in series with said inertia responsive switch and including a pair of electrically spaced terminals, yieldable conductive means arranged for normally electrically bridging said terminals to complete the firing circuit through said pressure responsive switch to said inertia switch, means forming a fluid filled compartment having a first flexible wall section and a second flexible wall section, duct means for communicating fluid pressure from about the torpedo to the outer surface of said first flexible wall section to cause inward deflection of the latter and by way of fluid flow in said compartment to cause outward deflection of said second wall section, an apertured partition member disposed in said compartment intermediate said wall sections for reducing the rate of said fluid flow and delaying deflection of the second wall section in response to said deflection of the first wall section, a piston member operatively connected to said yieldable means and said second wall section and constructed and arranged for movement responsive to the deflection of the second wall section to urge said yieldable means from bridging contact between said terminals to open said firing circuit through said pressure responsive switch when the pressure about the torpedo exceeds a predetermined value, an electrical source for energizing said firing circuit, time measuring means constructed and arranged to connect in said firing circuit said electrical source in predetermined time delayed relation to the actuation of said time measuring means, and a differential pressure responsive switch, conduit means connecting said last-named switch with the water surrounding the nose and side wall of the torpedo for actuating said time measuring means in response to a predetermined dynamic pressure differential in the surrounding water between the nose and side wall of the torpedo as the torpedo moves through the water.

24. In a torpedo exploder mechanism, the combination of a firing circuit including an electroresponsive detonator and means for closing the circuit, said means including an inertia responsive element and contact means substantially encircling the element, said element being mounted for substantially universal movement and adapted to be moved into engagement with said contact means in response to impact of the torpedo with a target vessel for closing the circuit and firing the detonator, and insulating means carried by said contact means beneath said element for preventing engagement of said contact means by said element in response to impact of the torpedo with the surface of the water following broach thereof.

25. In a torpedo exploder mechanism, the combination of a firing circuit including an elcctroresponsive detonator and an inertia switch for closing the circuit, said switch comprising a substantially universally movable inertia mass and a contact member substantially surrounding the mass, said mass being movable into contact with said member for firing the detonator in response to the set forward force resulting from impact of the torpedo with a target vessel, said switch also including insulating means interposed between said mass and said member at one side thereof for preventing contact therebetween in response to a lateral force resulting from impact of the torpedo with the surface of the water following a broach thereof.

26. In a torpedo, the combination of an electroresponsive detonator, an initially unarmed firing circuit connected to the detonator, time measuring means, said firing circuit including switch means actuated by said time measuring means for arming said firing circuit when the time measuring means has operated for an interval of time corresponding substantially to the time required for the torpedo to travel a predetermined distance through the water at a speed at least as great as a predetermined speed following launching thereof, a pressure difierential switch for setting said time measuring means in operation when the pressure of the surrounding water between the nose and side wall of the torpedo reaches a predetermined value, conduit means connecting said pressure differential switch with the water surrounding the nose and side wall of the torpedo, and an inertia responsive switch forming part of the firing circuit for rendering the armed firing circuit effective to fire the detonator as the inertia responsive switch is actuated in response to impact of the torpedo with a target vessel.

References Cited in the file of this patent UNITED STATES PATENTS 1,461,268 DeLaney et a1 July 10, 1923 1,623,475 Hammond Apr. 5, 1927 2,027,709 Slebos I an. 14, 1936 2,117,213 Rodanet May 10, 1938 2,291,236 Kilgour July 28, 1942 2,399,523 Van Atta et al Apr. 30, 1946 2,415,086 Detwiler Feb. 4, 1947 FOREIGN PATENTS 12,800 Great Britain of 1915 

